Biodegradation of Navy Blue-3G by Brevibacillus laterosporus MTCC 2298

Attempts have been made to decolorize widely used disperse azo dye Navy Blue-3G by the Brevibacillus laterosporus MTCC 2298. The 80% decolorization was observed within 48 h under static condition at the concentration 50 mg/L. No significant change in the decolorization performance was observed under shaking condition. Decolorization performance was steeply decreased at the higher concentration (1.0 g/L) even after extended incubation (66% respectively within 72 h). Maximum decolorization exhibited at 30 °C and in broad range of pH (i. e. 7.0–11.0). Complete inhibition of tyrosinase, no significant change in the activities of laccase and DCIP reductase where as significant increase in the activities of lignin peroxidase (54%), aminopyrine N-demethylase (122%) and MG reductase (50%) was found in the cells obtained after decolorization when compared to control cells (i. e. without dye addition). Biodegradation of dye was confirmed by the TLC (thin layer chromatography) and FTIR (Fourier Transform Infra Red) spectroscopy. Bromobenzene (m/z 156, RT 19.892), ester substituted aniline derivative (m/z 178, RT 20.492), meta-di nitro benzene (m/z 167, RT 21.550) and ortho benzene aniline derivative (m/z 169, RT 23.892) were the degradation products elected by GC-MS (Gas Chromatography-Mass Spectroscopy) analysis. Extracted degradation products were found to be non-toxic for three bacteria such as Brevibacillus laterosporus, Pseudomonas aeruginosa and Azotobacter vinelandii as well as for the two crops Sorghum vulgare and Phaseolus mungo.